High frequency oscillator



Aug. 18, 1936. 1.. TONKS 2,051,623

HIGH FREQUENCY OSCILLATOR Filed March 28, 1934 Inventor: Lewi Tonks.

His Attorney.

Patented Aug. 18, 1936 UNITED STATES H GH FREQUENCY OSCILLATOR LewlTonia, Schenectady, N. Y., minor to -Generai Electric Company, acorporation of New York Application March 28, 1934, Serial No. 717,741

My invention relates to high and frequency oscillators, and moreparticularly to such oscillators utilizing electric discharge devicescontaining an ionizable medium.

In the copending application of Irving Langmuir, Serial No. 717,747,filed concurrently herewith and assigned to the same assignee as thepresent'application, there is disclosed and claimed a high frequencyapparatus utilizing an electric *discharge device having an envelopecontaining an ionizable medium at a pressure sufllcient to produceionization without impediment to the free motion of electrons, and ananode, a cathode and a grid element within the envelope. The grid-"element of this discharge device, which is charged negatively withrespect to the anode so as to maintain a substantially continuouspositive ion sheath about the grid, is of such magnitude orconfiguration as to separate adequately the anode plasma from thecathode plasma. A plasma is generally defined as an electrically neutralbody comprising an ionized medium. The positive ion sheath about thegrid element is capable of preventing or interrupting an electron flowbetween the two plasmas without the necessity of deioniza-' tion of theionizable medium. When the charge on the grid is varied by analternating potential the edges of the positive ion sheath move back andforth during each cycle so that a small portion of each cycle the edgeat one side of the sheath moves up to the immediate proximity of thegrid. At this time, the electrons from one plasma pass through the gridto the other plasma. When this device is used in a suitable circuit,continuous oscillations of high and ultra-high frequencies may begenerated at a relativeLv high efficiency so as to produce a highintensity output.

My invention relates to a high frequency apparatus of the type disclosedin the aforementioned application, and constitutes a modification of thearrangement disclosed therein by means of which oscillations may beobtained.

In accordance with my invention, there is provided an electric dischargedevice having an envelope which contains an anode, a cathode, a gridelement and an ionizable medium at a pressure sufficient to permitionization without imped ing the free movement of electrons. On theexterior of that portion of the envelope which encompasses the anodeplasma a conductor member or metallic band is provided as a means forcoupling capacitively to the anode plasma the output circuit. A similarmetallic band is provided for the cathode plasma to operate as acapacitive coupling means between the circuit and 10 Claims. (01.250-36) ultra-high the cathode plasma. It has been found that by meansof the capacitive coupling members in the form of metallic bands animproved operation is obtained.

It is an object of my invention to provide an improved oscillatorutilizing an electric discharge device containing an ionizable mediumwhich will generate powerful oscillations of high and ultra h frequency.

It is another object of my invention to provide a new and improvedelectric discharge device.

The novel features which I believe to be characteristic of my inventionare set forth in particularity in the appended claims. My inventionitself, however, both as to its organization and method of operationtogether with further objects and advantages thereof, will be betterunderstood by reference to the following description taken in connectionwith the accompanying drawing in which the figure represents anoscillator embodying the preferred embodiments of my invention.

Referring to the figure of the drawing, I have illustrated therein ahigh frequency oscillation generator utilizing an electron dischargedevice having an envelope l0 containing an anode ii, a cathode II, agrid member l3, and an ionizable medium suflicient to permit a degree ofionization which will not present any substantial impedance to electronmovement. This ionizable medium may comprise mercury vapor atapressurepreferably within the range of 0.1 to 2 microns or one of therarer gases such as argon, neon, and the .like. In the instance of neonor helium the gas is at a pressure of the order of one millimeter ofmercury. It is to be understood that the grid element need not extend tothe walls of the envelope, inasmuch as any configuration which willseparate adequately the anode plasma from the cathode plasma willsuflice. On the exterior of that portion of the envelope whichencompasses the anode plasma a conductive member It is provided whichserves as a capacitive coupling member to the plasma which surrounds theanode II. This capacitive coupling member may comprise metallic stripspartially or totally surrounding the envelope of the discharge deviceand need not be contiguous to the envelope. A similar conductive memberI5 is provided on the exterior of that portion of the envelope whichencompasses the cathode plasma and-this conductive member serves as acapacitive coupling member to the plasma surrounding the cathode.Although the grid element I3, as illustrated, extends to the walls ofthe envelope, any other grid configuration will suffice if it separatesadequately the anode plasma from the cathode plasma. One example of suchgrid configuration would bea cylindrical grid closedat one endandlocated so as to enclose substantially the anode or'the cathode, andthis grid need not extendto the walls of the envelope. potential i6 isutilized to energize the cathode l2. The anode to cathode circuitincludes a source of anode potential I1 and a choke inductor I 8 whichprevents high frequency currents from being dissipated in this circuit.

The grid to cathode plasma circuit comprises a portion of an inductor l9and the lead 20 which is connected to the capacitive coupling member l5.cuit includes the remaining portion of the inductor l9, and the lead 20which is connected to the capacitive coupling member 15. A variablecapacitor 2! is connected between the grid 13 and the anode plasmacoupling member l4 so as to provide a means for determining thefrequency at which the oscillator will operate. In order to maintain thegrid at a suitable potential, a circuit including a source of potential22, a choke inductor 23 and a resistor 24 is connected between thecathode and a point on the grid circuit.- The choke inductor 23 preventshigh frequency current from being dissipated in this circuit. Theresistor 24 operates as a means for automatically initiating thegeneration of oscillations upon initial energization of the cathode l2by the source of potential 16.

In explaining the operation of the above de-. scribed oscillator, itwill be assumed that initially the cathode I2 is not energized. At thistime a'positive potential is impressed upon the anode l by the source ofpotential I! and a positive potential is also impressed upon the grid l3by the source 22. The potential impressed by the source 22 is the fullvalue of the source of potential inasmuch as no current is flowing inthe grid to cathode circuit with the result that the resistor 24 doesnot producean IR drop. As soon as the cathode I2 is energized itliberates free electrons which flow to the other elements of thedischarge device with the result that ionization occurs to cause plasmaformation and current flows through the grid-to-cathode circuit. Thisflow of current through the circuit produces a potential drop across theresistor 24 with the result that the grid [3 becomes sufllcientlynegative with respect to the anode ll so as to produce about the grid apositive ion sheath. This positive ion sheath divides the plasma intocathode and anode plasmas and interrupts the electron fiow between thecathode and the anode. This initiation and interruption of an electronflow between the cathode and the remaining elements of the dischargedevice has induced energy in the circuit [9, 2|, which will causefurther variations of the grid voltage at a frequency determined by theinductance of l 9, the capacity 2|, and the capacities existing betweenthe elements l3, l4 and I5 of the discharge device. During each portionof the cycle of the alternations impressed upon the grid |3 which causethe grid to assume a potential sufiicient to vary the positive ioncharge about the grid, afiow of electrons occurs between the anode andcathode. Thus, upon energization of the cathode l2 the resistor 24operates as a means for automatically initiating the generation ofoscillations.

It is to be understood that any other means may be substituted for thecircuit comprising the elements 22, 23 and 24, it being only necessary Asuitable source of The anode plasma to cathode plasma cir-.

to provide some means for maintaining normally under operatingconditions a potential upon the grid I3 suflicient to produce the properpositive anode and cathode plasmas as an output circuit.

While the theory and explanation of operation given in the aboveexplanation are believed to be correct, I do not wish to be limitedthereto.

' The arrangement disclosed and described here-- in is believed to havegreater efliciency and greater stability of operation than thearrangement disclosed in the above-identified copending application-ofIrving. Langmuir, and has the further advantage of separating theoscillating portions from the non-oscillating portions of the circuit.

While I have shown and described my invention in connection with certainspecific embodiments, it will, of course, be understood that I do notwish to be limited thereto, since it is apparent that the principlesherein disclosed are susceptible of numerous other applications, andmodifications may be madein the circuit arrangement and in theinstrumentalities employed without departing from the spirit and scopeof my invention as set forth in the appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A high frequency apparatus including a discharge device comprising anenvelope containing an ionizable medium at a pressure sufil cient topermit a degree of ionization suitable for plasma formation withoutmaterially impeding free electron movement, an anode, a grid and acathode included within said envelope, a source of potential connectedbetween said anode and said cathode, means for impressing a potentialupon said grid with respect to one of the other of said electrodes toproduce normally a substantially continuous positive ion sheath aroundsaid grid, said grid being of such configuration that said sheathseparates said ionizable medium into anode and cathode plasmas, meanscapacitively coupled to said cathode plasma, means capacitively coupledto said anode plasma, a circuit connected between said grid and saidcathode plasma coupling means, and a circuit connected between saidcathode plasma and said anode plasma coupling means.

2. A high frequency oscillator including a discharge device comprisinganode, cathode and grid elements enclosed within an envelope containingan ionizable medium at a pressure sufllcient to permit ionizationwithout material impediment to electron movement, a source of potentialconnected between said anode and said cathode,means for impressing apotential upon said grid with respect to one of the other of saidelectrodes to produce normally a substantially continuous positive ionsheath around said grid, said grid being of such magnitude andconfiguration as to separate said envelope into anode and cathodecompartments, means for capacitively coupling circuits to said anode andsaid cathode compartments, a circuit connected between 'said grid andsaid cathode compartment coupling means, a second circuit connectedbetween saidanode compartment coupling means and said cathodecompartment coupling means, and means for transferring a portion of theenergy in said second circuit to said first circuit whereby oscillationsare generated.

3. A high frequency oscillator including a discharge device comprisingan envelope containing an ionizable medium at a pressure sufiicient topermit a degree of ionization suitable for plasma formation withoutmaterially impeding free electron movement, an anode, a grid and acathode included within said envelope, a source of potential connectedbetween said anode and said cathode, means for impressing a potentialupon said grid with respect to one of the other of said electrodes toproduce normally a substantially con-' tinuous positive ion sheatharound said grid, said grid having such configuration that said sheathseparates said ionizable medium into anode and cathode plasmas, meanscapacitively coupled to,

said cathode and said anode plasmas, a circuit connected betweensaidgrid and said cathode plasma coupling means, a circuit connectedbetween said cathode and said anode plasma coupling means, and meansfortransferring a portion of the energy in said latter circuit to saidformer circuit.

4. A high frequency oscillator including a discharge device comprisingan envelope containing an anode, a cathode, a grid element, and anionizable medium at a pressure sufilcient to permit ionization withoutmaterial impediment to free electron motion, a source of potentialconnected between said anode and said cathode, means for energizing saidcathode, means operable upon energization of said cathode for producingabout said grid a substantially continuous positive ion sheath, saidgrid having such configuration that said sheath divides said ionizablemedium into anode and cathode plasmas, a plurality of'metallic memberscapacitively coupled to said anode and said cathode plasmas, a circuitconnected between said grid and said cathode metallic member, a secondcircuit connected between said an-- ode metallic member and said cathodemetallic member, means for tuning at least one of said circuits, meansfor transferring a portion of the energy of said second circuit to saidfirst circuit, and means for confining the high frequency energy to saidcircuits.

5. A high frequency oscillator including a discharge device comprisingan envelope containing an anode, a cathode, a. grid element of suchconfiguration as to divide said envelope into anode and cathodecompartments and an ionizable medium at a sufllcient pressure to permitionization and the formation of plasma without materially impeding themotion of electrons, means including a source of anode potential forproducing plasmas surrounding each of said cathode and anode elements, aplurality of conductive members capacitively coupled to said anode andsaid cathode plasmas, means for producing normally a positive ion sheathabout said grid to separate said plasmas thereby normally restrictingthe flow of electrons therebetween, a circuit connected to said grid andcapacitively coupled tosaid cathode plasma by one of said conductivemembers, a second circuit capacitively coupled to said anode and saidcathode-plasmas by said conductive members, means for tuning at leastone of said circuits, and means for transferring energy from said secondcircuit to said first circuit whereby said positive ion sheath will bealtered periodically to cause a fiow of electrons between said plasmas.I

6. A high frequency oscillator including a discharge device comprisingan envelope containing an anode, a cathode, a grid element and anionizable medium at a pressure sufiicient to permit ionization andplasma formation, without materially impeding the motion of freeelectrons, means including a source of anode potential for producingplasmas surrounding eac of said cathode and said anode elements, aconductive member capacitively coupled to said cathode plasma, a circuitconnected between said member and said grid, a conductive membercapacitively coupled to said anode plasma, a circuit connected be-vtween said latter member and said cathode plasma member, means fortransferring a portion of I the energy of one of said circuits to theother of said circuits, means for tuning at least one of said circuits,means for confining the high frequency energy to said circuits, meansfor energizing said cathode, and means for producing normally uponenergization of said cathode, a charge on said grid negative withrespect to said anode.

'7.'An electric discharge device comprising an envelope containing acontrol grid element, at one end an anode, and at the other end acathode, and an electrically conductive member mounted exteriorlyadjacent to said envelope in the proximity of said cathode, and a secondelectrically conductive member located exteriorly adjacent to saidenvelope in the proximity of said anode.

8. An electric discharge device comprising an envelope containing anionizable medium at a pressure sufiicient to permit ionization withoutmaterial impediment to free electrons, a control grid element, an anodeat one end, and a cathode at the other end, and a plurality of metalmembers mounted exteriorly adjacent to said envelope in the proximitiesof said anode and said cathode, respectively.

9. An electric discharge device comprising an envelope containing anionizable medium, an anode, a cathode and a control grid element, saidgrid element having such configuration as to separate said envelope intoanode and cathode compartments, and a metallic member mounted on theexterior of said envelope in the proximity of said anode.

10. An electric discharge device comprising an envelope containing ananode, a cathode and a grid element, said grid element being of suchconfiguration as to separate said envelope into anode and cathodecompartments, and a plurality of metal bands mounted on the exterior ofsaid envelope, one of said metal bands being located in the proximity ofsaid anode and the other of said metal bands being located in theproximity of said cathode.

LEWI TONKS.

